A multichannel biosensor instrument for rapid, specific, and sensitive detection of microorganisms, macromolecules, and small molecules is described. It uses highly efficient capillary bioseparators/bioreactors to specifically capture and separate target biological and/or chemical agents (including bacteria, viruses, proteins, toxins, pesticides, antibiotics, etc.) from food, environmental, or clinical samples and to quickly generate quantitative optical signals. The applications of the biosensor system include, but are not limited to, rapid detection of food pathogens, protein biomarkers, and pesticide residues.
Microbial contamination of food products by pathogenic bacteria remains a major concern of our society. Contaminated food is estimated to cause 76 million illnesses, with 325,000 serious illnesses resulting in hospitalization, and 5,000 deaths in the United States each year. Although conventional culture methods hypothetically allow the detection of a single cell of specific pathogens, these methods are extremely time-consuming, typically requiring at least 24 h and involve complicated multi-steps to confirm the analysis. Even current rapid methods such as ELISA and PCR still require enrichment of samples for 8-24 h and take several hours to get only qualitative (positive/negative) results. These methods also require elaborate laboratory setup and highly skilled personnel. Since current food processing and distribution systems operate at a very high speed and the infectious dosage of some foodborne pathogens are very low, it is extremely important to develop new, rapid yet sensitive methods for the detection of pathogens in food products. This is a critical step in ensuring the safety of the food supply.
As we move into the post-genomic era, there is an increasing need to identify specific proteins and investigate the relationships between protein expressions and specific cellular processes. Western blot analysis and two-dimensional gel electrophoresis (2-DE) followed by matrix assisted laser desorption ionization/time of flight (MALDI/TOF) mass spectrometry (MS) analysis are both powerful tools in proteomics research. The 96- or 384-well ELISA, immunobeads based flow cytometry, protein microarrays, etc. are also frequently used for high-throughput protein detection. However, many problems still plague these methods including the requirement of expensive or large equipment (e.g., 2-DE MALDI/TOF MS), extensive sample pretreatment (e.g. flow cytometry), intensive manual operations (e.g. ELISA), highly skilled personnel, or lack of appropriate sensitivity (e.g. protein microarray).
The potential hazard of pesticides makes it vital to monitor residues in drinking water, the food supply, and the environment. HPLC and GC are standard methods for detection of pesticide residues. These methods are reliable and have adequate sensitivity or detection limits required by the regulatory standards. However, these methods require extensive sample preparation and pre-concentration as well as expensive instrumentation and skilled personnel.